Jacketed lamp mount frame clip

ABSTRACT

A jacketed lamp comprising an inner envelope centrally supported within a vitreous outer envelope having a bulb portion domed at one end and necked at the other to which a base is attached. The mount frame for the inner envelope extends from an inlead sealed through the stem at the base end to a dimple formed in the bulb at the dome end. The mount frame engages the dimple by a clip comprising a springy metal band formed into a closed noncircular loop. The loop deforms towards a more circular shape to resiliently engage the dimple and accommodate dimensional variations.

United States Patent [191 Fitzgerald [451 Jan. 15,1974

[ JACKETED LAMP MOUNT FRAME CLIP [75] Inventor: Nelson Fitzgerald, Euclid, Ohio [73] Assignee: General Electric Company,

Schenectady, NY.

221 Filed: Dec. 26, 1972 21 Appl. No: 318,261

[52] US. Cl 313/292, 313/184, 313/227 [51] Int. Cl. H0lj l/88 [58] Field of Search 313/184, 227, 292

[56] References Cited UNITED STATES PATENTS I 3,409,790 11/1968 Gottschalk 313/292 Primary ExaminerH. K. Saalbach Assistant Examiner-Darwin R. Hostetter Attorney-Ernest W. Legree et a1.

[57] ABSTRACT A jacketed lamp comprising an inner envelope centrally supported within a vitreous outer envelope having a bulb portion domed at one end and necked at the other to which a base is attached. The mount frame for the inner envelope extends from an inlead sealed through the stem at the base end to a dimple formed in the bulb at the dome end. The mount frame engages the dimple by a clip comprising a springy metal band formed into a closed noncircular loop. The loop deforms towards a more circular shape to resiliently engage the dimple and accommodate dimensional variations.

8 Claims, 3 Drawing Figures JACKETED LAMP MOUNT FRAME CLIP BACKGROUND OF THE INVENTION The invention relates to electric discharge lamps having an inner envelope mounted in a vitreous outer envelope or jacket, and especially to the mount frame or structure for supporting the inner envelope. It is of particular interest for high intensity lamps which generally comprise a quartz or ceramic arc tube enclosed within a glass outer jacket fitted with a screw base at one end. Such lamps include high pressure metal vapor lamps utilizing quartz arc tubes to contain fillings of mercury or metal halides, and high pressure sodium vapor lamps utilizing ceramic arc tubes to contain fillings of sodium and mercury.

A common shape of outer envelope for jacketed lamps is a bulb domed at one end and necked at the other to which a screw base is attached. At the center of the domed end there is provided a dimple or inwardly turned nipple which is used to brace the mount frame which supports the arc tube. The mount frame extends from an inlead sealed through the stem at the base end to the dimple at the dome end which it engages by a clip device. Such a mount using a hexagonal open-sided clip is described in US. Pat. No. 3,409,790 -'Gottschalk,' Arc Tube Mounting, November 1968.

SUMMARY OF THE INVENTION The object of my invention is to provide an improved clip means for achieving interengagementof the mount and dimple, which affords a secure fastening, is economical to manufacture, and lends itself to manual assembly or to automated assembly when desired.

According to my invention, the dimple is engaged by a clip comprisinga closed resilient metal loop attached to the forward end of the mount frame. The loop is formed to a noncircular pattern and achieves resilient engagement with the dimple bydeforming towards a circular pattern. Dimensional variations in the dimple are accommodated by more or towards the circular. v

In a preferred embodiment, the closed loop is 'a springy tempered steel band spot-welded to the forward end of the mount frame in a generally pearshaped pattern, that is, more elliptical at one end and more conical at the other. As the loop is engaged by the dimple, it is deformed towards the circular, the larger the dimple, the greater the deformation.

DESCRIPTION OF DRAWING FIG. 1 is a section side view of a high pressure metal vapor arc lamp embodying the invention in preferred form.

FIG. 2 is an enlarged end sectional view showing the undeformed loop.

FIG. 3 is an enlarged end sectional view looking upon line 3-3 in FIG. 1 and showing the loop engaged by the dimple.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawing and more particularly to FIG. 1, there is shown a high pressure mercury vapor lamp 1 embodying the invention in preferred form. It comprises a vitreous envelope or jacket 2 of ellipsoidal shape having a neck 3 to the end of which is attached a screw-type base 4. The neck 3 is closed by a reless deformation entrant stem 5 having a press portion 6 through which extend relatively stiff inlead wires 7, 8 connected to the contact surfaces of the base, namely the insulated center contact or eyelet 9 and the base shell 11. At the domed end of the glass envelope, there is provided a dimple or inverted nipple 18 of generally cylindrical configuration.

Inner arc tube 12 is made of quartz and encloses a charge of mercury and an inert starting gas, suitably argon at a pressure of about 20 torr. It is provided at opposite ends with a pair of main discharge supporting electrodes l3, 14 to which connections are made by ribbon-type inleads sealed through the flattened ends of the tube. Each main electrode comprises a tungsten coil containing an electron emitting mixture such as alkaline earth oxides in the interstices between turns. A fine tungsten wire 15 sealed into the arc tube at its lower end serves as an auxilary starting electrode and is connected through a current limiting resistor 16 to inlead 7 by way of side rod 17. The side rod is welded to inlead 7 at the base end and extends to anchoring dimple 18 at the dome end of the envelope which, in accordance with the invention, it engages by aclosed springy loop 19. The are tube is supported in the mount frame or narness by clamping its flat ends between metal bands 21, 22 which are welded to side rod 17. Outer envelope 2 may be coated internally with a phosphor layer 23 and may be either evacuated or filled with an inactive gas such as nitrogen.

The main function of clip loop 19 is to anchor the forward end of the mount frame to envelope 2 by engaging dimple 18. However optimum design requires that it satisfy a number of ancillary requirements. It should act as a shock absorber for the mount, both in shipping and under normal operating conditions. It must accommodate itself to variations in the size of the dimple resulting from variables in glass bulb manufacture. The dimple is pressed into the hot formed bulb while plastic at the dome end by a plunger and its size willvary with the thickness of the glass. For example, manufacturing tolerances for a 400 watt size of bulb permit the dimple diameter measured inside the bulb to vary from 0.58 inch to 0.67 inch, corresponding to a range of about 15 percent.

In lampmaking, the assembly of the stem 5, inlead wires 7, 8, side rod 17, and attached arc tube 12 is known as the mount assembly. When the mount assem' bly is inserted into envelope 2, dimple 18 must enter into and be encircled by clip loop 19, and thereafter the envelope is sealed by heat-fusing the flare of the stem to the neck. The engagement of the dimple must not be too rigid norcan it be too loose. If the clip loop is too rigid, the dimple will not enter it and the mount structure will bend resulting in a defective lamp. However a loose fit of the clip on the glass dimple will create what is known as a rattler and this is likewise considered a serious defect. While the hexagonal shaped spring clip of the Gottschalk patent did achieve a rattlefree engagement between the mount and the dimple, its shaping and material resiliency were critical. Also forming, feeding and welding by automated machinery posed substantial problems.

In the preferred illustrated embodiment of my invention, the clip, best seen in FIGS. 2 and 3, comprises a closed loop 19 formed of a band of spring tempered stainless steel. Suitable stainless steels are Type 301 containing 16-18 percent chromium and 6-8 percent nickel, and Type 302 containing l7-l9 percent chromium and 8-10 percent nickel, in full hard temper, that is spring tempered. The material is received as ribbon 0.010 inch thick by three-sixteenth inch wide; it has a bright finish and maintains its temper at the elevated temperatures encountered. A length of ribbon is used which exceeds the maximum circumference of the dimple permitted by manufacturing tolerances plus the excess needed to make the attachment to side rod 17. For a 400 watt size of lamp having the dimple dimensions and tolerance previously stated, a length of about two and three-eighths inches is suitable. The end of side rod 17 is flattened to about 60 percent of its original thickness at a slight angle to the plane of the mount to compensate for the offset of the mount to one side of inlead 7. The loop band is preferably double spot welded on both sides of the flat as indicated at 24, 25.

A preferred configuration for the loop when not engaged by the dimple is a pear-shaped one, that is one having a contour which is generally more elliptical at one end and more conical at the other, as shown in H6. 2. This configuration is more readily achieved if the ribbon is bent about 30 to a small radius at 26, 27 prior to welding to side rod 17. The narrow dimension of the loop should be less than the minimum diameter of dimple (represented by broken line circle 18 in FIG. 2) according to manufacturing tolerances, that the clip must engage. Thus when the dimple enters the loop, it causes the flatter sides 28, 29 to expand out resulting in a resilient engagement, as shown in FIG. 3. The circumference of the loop should be great enough that when the loop is expanded to the point where it is substantially circular, it will accommodate the largest dimple allowed by manufacturing tolerances.

While the dimple loop attachment according to my invention has been illustrated in connection with a mercury vapor lamp, it is equally usable with other double envelope lamps such as metal halide almps, high pressure sodium vapor lamps utilizing ceramic envelopes, and regenerative halogen cycle incandescent filament lamps which have the same requirement of engaging an anchoring dimple in the dome end of the bulb in order to brace the mount.

What I claim as new and desire to secure by Letters patent of the United States is:

l. A jacketed electric lamp comprising a vitreous outer envelope having a neck end with inleads sealed therethrough and a dome end with a dimple therein;

an inner envelope within said outer envelope;

at mount frame supporting said inner envelope within said outer envelope including a metal member extending from an inlead at the neck end to said dimple at the dome end;

and clip means for resiliently anchoring said mount frame to said dimple comprising a loop of springy material attached to said mount frame and encircling said dimple, said loop having, when disengaged from said dimple, a noncircular pattern whose circumference exceeds that of the dimple and whose minimum transverse dimension is less than that of the dimple.

2. A lamp as defined in claim 1 wherein said-loop is made of a thin band of tempered steel.

3. A lamp as defined in claim 1 wherein said loop is made of a thin band of tempered steel formed to a pattern, which, when disengaged from the dimple, is more elliptical at one end and more conical at the other and has a minimum transverse dimension less than the dimple.

4. A jacketed electric lamp comprising a vitreous outer envelope having a neck end with inleads sealed therethrough and a base attached thereto, and a dome end with an inwardly turned projecting dimple therein 1 of generally cylindrical configuration having a diameter variable between preset tolerance limits;

an inner envelope within said outer envelope having connections through said inleads to said base;

a mount frame supporting said inner envelope within sald outer envelope including a metal member extending from an inlead at the neck end to said dimple at the dome end;

and clip means for resiliently anchoring said mount frame to said dimple comprising a loop of springy material attached to said mount frame and encircling said dimple, said loop having, when disengaged from said dimple, a noncircular pattern whose circumference exceeds that of the dimple at the maximum tolerance limit and whose minimum transverse dimension is less than that of the dimple at the minimum tolerance limit.

5. A lamp as defined in claim 4 wherein said loop is made of a thin band of tempered steel.

6. A lamp as defined in claim 4 wherein said loop is made of a thin band of one of Type 301 and Type 302 stainless steel in full hard temper.

7. A lamp as defined in claim 4 wherein said loop is made of a thin band of tempered steel formed to a pattern, which, when disengaged from the dimple, is more elliptical at one end and more conical at the other and has a minimum transverse dimension less than the dimple at the minimum tolerance limit.

8. A lamp as defined in claim 4 wherein the range covered by said tolerance limits is within 15 percent. 

1. A jacketed electric lamp comprising a vitreous outer envelope having a neck end with inleads sealed therethrough and a dome end with a dimple therein; an inner envelope within said outer envelope; a mount frame supporting said inner envelope within said outer envelope including a metal member extending from an inlead at the neck end to said dimple at the dome end; and clip means for resiliently anchoring said mount frame to said dimple comprising a loop of springy material attached to said mount frame and encircling said dimple, said loop having, when disengaged from said dimple, a noncircular pattern whose circumference exceeds that of the dimple and whose minimum transverse dimension is less than that of the dimple.
 2. A lamp as defined in claim 1 wherein said loop is made of a thin band of tempered steel.
 3. A lamp as defined in claim 1 wherein said loop is made of a thin band of tempered steel formed to a pattern, which, when disengaged from the dimple, is more elliptical at one end and more conical at the other and has a minimum transverse dimension less than the dimple.
 4. A jacketed electric lamp comprising a vitreous outer envelope having a neck end with inleads sealed therethrough and a base attached thereto, and a dome end with an inwardly turned projecting dimple therein of generally cylindrical configuration having a diameter variable between preset tolerance limits; an inner envelope within said outer envelope having connections through said inleads to said base; a mount frame supporting said inner envelope within saId outer envelope including a metal member extending from an inlead at the neck end to said dimple at the dome end; and clip means for resiliently anchoring said mount frame to said dimple comprising a loop of springy material attached to said mount frame and encircling said dimple, said loop having, when disengaged from said dimple, a noncircular pattern whose circumference exceeds that of the dimple at the maximum tolerance limit and whOse minimum transverse dimension is less than that of the dimple at the minimum tolerance limit.
 5. A lamp as defined in claim 4 wherein said loop is made of a thin band of tempered steel.
 6. A lamp as defined in claim 4 wherein said loop is made of a thin band of one of Type 301 and Type 302 stainless steel in full hard temper.
 7. A lamp as defined in claim 4 wherein said loop is made of a thin band of tempered steel formed to a pattern, which, when disengaged from the dimple, is more elliptical at one end and more conical at the other and has a minimum transverse dimension less than the dimple at the minimum tolerance limit.
 8. A lamp as defined in claim 4 wherein the range covered by said tolerance limits is within 15 percent. 